Frank g



(No Model.)

F. G. NELSON. CALCULATOR.

No. 526,196. Patented Sept. 18, 1894.

' I I B NrTnn STATES PATENT OFFICE.

FRANK G. NELSON, OF NEl/V YORK, N. Y.

CALCU LATO R.

SPECIFICATION forming part of Letters Patent No. 526,196, datedSeptember 18, 1894.

Application filed March 1, 1894. Serial No. 501,910- (No model.)

To all whom it may concern:

Be it known that I, FRANK G. NELSON, a citizen of the United States,residing at New York city, in the county and State of New York, haveinvented a new and useful Calculator, of which the following is aspecification.

My invention relates to the simplification of calculations in caseswhere a constant divisor or multiplier is to be used for severalsuccessive operations; and the objects of my invention are, first, toavoid repetition of the more difficult processes of division andmultiplication by substituting therefor the easier process of addition,and, second, to escape the labor and liability to error incurred inascertaining and setting down the figures of each operation,intermediate between those given and those required, by setting down onthe calculator, once for all, before beginning the work, the ninepossible combinations of figures by means of which all of the operationscan be performed. I attain these objects by the mechanism illustrated inthe accompanying drawings, in which Figure 1 is a View in perspective ofthe calculator. Fig.2 is a plan, with the larger section of the slidingcover removed and with the necessary slides so adjusted as to obtain adesired result; and Fig. 3 is a view of the right hand end of thecalculator, with the end of the box removed.

The same letters refer to the same or similar parts throughouttheseveral views.

The shallow box contains parallel, beveled guides, c, fastened to thebottom thereof, between which there are retained by means of a reversebevel, nine or more movable slides, d. Each slide has a peg orprojection, g, at its right hand end for convenience in moving it thepegs being numbered consecutively down- Ward with the nine digitsand asurface of ivory, silicate, slate, or other erasable material coveringthe left hand half thereof. The upper surfaces of the slides and guidesmay be marked by equidistant cross-rulings for convenience in movingeach slide to any desired position.

The sliding cover is divided into two parts, A and B, the former ofwhich is removed when the calculator is to be used, while the latter isretained to cover up the figures that are not to be used and to carry totheright 1 1 also be had from a or from xa, and if several numbers, a,b, c, d, 850., are to be divided by y, multiplying successively by eachof them will readily give the desired results.

The words upper slide hereinafter used are intended to signify the slidefarthest from the operator and by the word vertically I mean in a lineacross the face of the calculator.

The figures of the reciprocal of the divisor are written with a softpencil upon the upper slide of the calculator, the first significantfigure being one place removed from the left hand end of the slide. Uponthe second slide twice the reciprocal is written; on the third, threetimes it; and so on down to the ninth slide on which nine times thereciprocal is written.

All of the slides and the short section of the sliding cover being atthe extreme right hand end of the box, push to the left hand end thatslide whose peg bears the first figure of the dividend or the figure ofhighest order. This will carry the cover over the figures of the unusedslides. Then push the slide corresponding to the second figure of thedividend over to within one space of the left hand end of the box, theslide corresponding to the third dividend figure over to within twospaces of the end, and so on until slides have been moved for all of thefigures of the dividend. Add vertically the exposed figures on theslides; set down the sum, point off the decimal figures correctly, andthe desired quotient is obtained.

The sliding cover in being moved back to the right hand end carries withit all of the slides that have been used and the calculator is ready forthe next operation.

A more comprehensive rule covering all possible contingencies is this,all slides and the cover being at the extreme right hand of the box:Move the slides to the left hand so that the figures on the pegs of theslides which have been moved when added vertically produce the dividend;then the exposed figures on the slides when added vertically and pointedoft correctly will give the quotient. If one or more ciphers appeal-inthe dividend the slides for the figures after the ciphers must be setback one or more places accordingly. If a figure occurs more than once,although there is only one slide for that figure, the proper combinationof other slides can generally be easily made.

In Fig. 2 of the drawings the calculator is arranged to reduce fourmillion two hundred and two thousand two hundred and eleven feet tomiles by dividing that number by five thousand two hundred and eighty,that is, the reciprocal of five thousand two hundred and eighty isplaced on slide one, its product by each of the other digits on thecorresponding slides, and the slides have been moved so that the figureson the pegs of the moved slides added vertically give the dividend,while the exposed numbers on the slides added vertically give 7921873292miles, the result being carried out to six decimal places. Sometimes adividend is encountered which cannot be formed from the figures on thepegs, nine hundred and ninety-nine thousand nine hundred andninety-nine, for instance. If such cases are infrequent the difficnltycan be overcome by cutting the dividend in two and finding separatequotients for the first group of figures and for the group of theremaining figures, which quotients can be added together afterward; butif these cases occur frequently it is advisable to have one or moreauxiliary slides on the upper side of the calculator with their pegsnumbered with the smaller digits. No rule is given here for pointing offthe quotient because inspection will always show the proper place forthe decimal point. X'Vhen all of the operations have been performed, adamp cloth or sponge will remove the penciled figures from the slides.

In using the calculator for multiplying, the foregoing description ofthe process will apply in every respect, if the word multiplier issubstituted for reciprocal of the divisor, multiplicand for dividend andproduct for quotient.

Having fully described my invention, what I claim, and desire to secureby Letters Patent, is-- 1. A calculator, consisting of a shallow box,with beveled guides fastened to its bottom, retaining nine or morebeveled slides, all substantially as described.

2. A calculator, each slide of which has a surface of ivory, silicate,slate or other erasable material, covering its left hand hall, and a pegor projection, numbered with one of the nine digits, at its right handend, for convew ience in moving it, and for moving, and be ing moved by,the sliding cover, all substantially as described.

3. A calculator, having a box or base provided with guides, slides tomove in said guides, the guides and erasable surface of the slides ofwhich are marked by equidistant cross-rulings for convenience in movingeach slide to any desired position and in making vertical additions, allsubstantially as de scribed.

4:. A calculator, with a slidingcover divided into two parts, one ofwhich is retained over the slides when in use to cover up the figureswhich are not used, in each operation, and to carry all of the slides,which have been moved, to the right hand end of the calculator, aftereachoperation, all substantially as described.

FRANK G. NELSON.

Witnesses:

FRANK POWELL, WILLARD GRAHAM.

